1. Field of the Invention
The present invention relates to a non-contact integrated circuit card and, more specifically, to a non-contact integrated circuit card that incorporates a battery as a power supply.
2. Description of the Related Art
The construction of a conventional non-contact integrated circuit card is shown in FIG. 6. A CPU 1 for processing data and for controlling the operation of the card is connected with a ROM 2 and a RAM 3 via a bus 8. The ROM 2 is provided for storing programs, while the RAM 3 is provided for storing data. The bus 8 is connected with an input-output (I/O) control circuit 5 for controlling the inputting of data from and outputting of data to an external apparatus (not shown). The I/O control circuit 5 is connected, via a modulation/demodulation circuit 6, with an antenna 7. The card also includes a battery 4 incorporated therein for supplying electrical energy to the above-described electric circuits.
With such a card, when a signal to be input, which is in the form of an electromagnetic wave, is received from an external apparatus by the antenna 7, the signal is digitized by the modulation/demodulation circuit 6. Thereafter, the signal is input to the CPU 1 via the I/O control circuit 5. The CPU 1 processes the input signal in accordance with the programs stored in the ROM 2, and stores data in the RAM 3 in accordance with necessity. Data to be output in response to an external apparatus, such as the results of processing, are supplied, via the I/O control circuit 5, to the modulation/demodulation circuit 6, in which the data are converted into analog equivalents. Thereafter, the data are transmitted as electromagnetic waves via the antenna 7 to the external apparatus.
In order that the card can receive a signal from an external apparatus and process the input signal, each of the electric circuits incorporated in the card must always be supplied with electric current from the battery 4 so that the card stands by in its state of being capable of receiving. However, after the battery 4 is incorporated in the card during the manufacturing of the card, the flow of electric current from the battery 4 continues even before the shipment of the card. Therefore, the energy produced by the battery 4 is rapidly consumed.
Because of the shape of the card, the battery 4 incorporated therein must be very thin. For this reason, it is impossible to incorporate a battery having a large current capacity. Furthermore, since the outer periphery of the card is normally enclosed by an outer cover made of plastic or the like, it is impossible to replace the battery 4 with a new battery.
Consequently, the conventional card has a problem in that the life of the battery 4 after the card is placed on the market, that is, the period during which the card is usable, is short. Another problem is that the durability of the batteries of the cards placed on the market varies depending on the length of the period from the incorporation of the battery 4 in the card to the shipment of the card.